Treatment as Prevention

Pre-exposure prophylaxis (PrEP) for HIV negative people was the biggest topic in HIV prevention in 2014, but use of antiretroviral therapy by HIV positive people to prevent onward transmission of the virus -- dubbed treatment as prevention or TasP -- also received further support.

More than 100 participants packed the Eureka Valley Recreation Center in San Francisco on May 20 for the latest Real Talk discussion of new HIV prevention strategies including pre-exposure prophylaxis (PrEP) and antiretroviral treatment as prevention.

No cases of linked HIV transmission were seen during 44,500 condomless sex acts by more than 750 heterosexual and gay couples, according to findings from the PARTNER study presented this week at the Conference on Retroviruses and Opportunistic Infections (CROI 2014).

An analysis of more than 750 serodiscordant heterosexual and gay couples in the PARTER study who engaged in more than 45,000 condomless sex acts found no cases of linked HIV transmission when the positive partner was on effective antiretroviral therapy (ART), confirming that treatment as prevention works, according to a report at the 21st Conference on Retroviruses and Opportunistic Infections (CROI 2014) this week in Boston.

A large study of heterosexual and gay couples saw no cases of linked HIV transmission during 44,500 condomless sex acts when the positive partner was on combination antiretroviral therapy (ART) with suppressed viral load, according to a presentation at the 21st Conference on Retroviruses and Opportunistic Infections (CROI 2014) this week in Boston. Based on these findings, there is no reason for legal action against people not using condoms while on effective ART.

Jens Lundgren from the University of Copenhagen reported the first findings from the PARTNER study, looking at HIV transmission within more than 750 serodiscordant couples -- together contributing nearly 900 years of follow-up -- who reported not using condoms.

While this much condomless vaginal and anal sex would be expected to lead to 50 to 100 transmissions, based on historical data, the researchers did not see any cases of linked transmission in which newly acquired HIV matched a partner's strain.

While the risk of transmission per sex act while on ART fell to nearly zero, the cumulative risk over time must still be considered. Lundgren said. Estimates of risk over 10 years may reach as high as 1 in 25 overall, or up to 1 in 10 for anal sex. Whether this level of risk is acceptable "is not for us to say, but for people to decide," he said.

Lundgren emphasized, however, that there is "no reasonable legal action you can take against people for not using condoms" if they are on effective ART, and no indication for post-exposure prophylaxis (PEP) in this situation.

These findings support the recent decision by the Centers for Disease Control and Prevention (CDC) -- at the urging of activists -- to refer to "condomless sex" rather than "unprotected sex," recognizing that there are other effective prevention approaches besides condom use.